code: def rgb2lab(rgb, dtype=None):
      """
      lab = rgb2lab(rgb, dtype={float})
  
      Convert sRGB to L*a*b* coordinates
  
      https://en.wikipedia.org/wiki/CIELAB
  
      Parameters
      ----------
      rgb : ndarray
          Must be of shape (h,w,3)
      dtype : dtype, optional
          What dtype to return. Default will be floats
  
      Returns
      -------
      lab : ndarray
      """
      return xyz2lab(rgb2xyz(rgb), dtype=dtype)
  
file_path: mahotas/mahotas/colors.py
imports: from __future__ import division
  import numpy
  from .internal import _check_3
label_desc: Use image node_id 6 for calling a global function with example usage: rgb2lab(rgb, dtype) and returns: xyz2lab